Multiple Choice problems related to Momentum and force.

1. Which of the following has the largest momentum relative to earth?
a. a pickup truck speeding along a highway
b. science building on campus
c. a tightrope walker crossing Niagara falls
d. a dog running down the street
e. a Mack truck parked in a parking lot.

2. A rifle recoils while firing a bullet. The speed of the rifle's recoil is small since
a. rifle has much more mass than the bullet
b. momentum of the rifle is smaller
c. momentum is mainly concentrated in the bullet
d. force against the rifle is smaller than against the bullet

3. In order to catch a ball, a baseball player extends the hand forward before impact with the ball and then lets it ride backward in the direction of the ball's motion. Doing this reduces the force of impact on the player's hand principally as the
a. time of impact is increased
b. time of impact is decreased
c. relative velocity is less
d. force of impact is reduced
e. none of these

4. Padded dashboards in cars are safer in an accident that non-padded ones as of occupant hitting the dash has
a. increased time of impact
b. increased momentum
c. decreased impulse
d. decreased time of impact

5. A 4 kg ball has momentum of 12 kg m/s. what is ball's speed?
a. 4m/s
b. 48 m/s
c. 3 m/s
d. 12 m/s
e. none of these

6. A 1 kg chunk of putty moving at 1m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with the momentum of
a. 5 kg m/s
b. 0 kg m/s
c. 1 kg m/s
d. 2 kg m/s
e. more than 5 kg m/s

7. Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?
a. 0
b. twice the sum of their original momentums
c. half sum of their original momentums
d. impossible to determine without additional information

8. An astronaut, floating alone in outer space, throws a baseball. If the ball floats away at a speed of 20meters per second, the astronaut will
a. move in the opposite direction at the speed of 20 m/s
b. move in the opposite direction but at the higher speed
c. move in the opposite direction, but at the lower speed
d. not move as stated in any of a the above choices

9. A 5000 kg freight car moving a 2 m/s runs into a 10,000-kg freight car at rest. They couple upon collision and move away as one body at
a. 1 m/s
b. 1/3 m/s
c. 2 m/s
d. 2/3 m/s

10. The change in momentum, in kg m/s, that occurs when a 1kg ball travelling at 4.0m/s strikes a wall and bounces back at 2 m/s is
a. 6
b. 4
c. 8
d. 2

11. If you push for a half hour or a whole hour against a stationary wall
a. twice as much work is done during the half hour
b. half as much work is done during the half hour
c. no work is done in either case
d. it is impossible to determine how much work is done

12. If you push an object twice as far while applying the equal force, you do
a. four times as much work
b. half as much work
c. twice as much work
d. the same amount of work

13. A job is done slowly, while an identical job is done quickly. Both jobs require the same amount of work, but different amounts of
a. power
b. energy
c. effort
d. none of these

14. Do 100 J of work in 50 s and your power output is
a. 4w
b. 5,000w
c. 2w
d. 50w
e. 1/2w

15. A 1000 kg car and a 2000 kg car are hoisted the same distance. Raising the more massive car require
a. as much work
b. less work
c. twice as much work
d. four times as much work
e. more than four times as much work

16. An object that has kinetic energy must be
a. at rest
b. falling
c. moving
d. at an elevated position
e. none of these

17. An object may have potential energy because of its
a. at rest
b. momentum
c. acceleration
d. location
e. none of these

18. A bow is drawn so that it has 40 J of potential energy. When fired, the arrow would ideally have kinetic energy that is
a. less than 40 J
b. 40 J
c. more than 40 J
d. impossible to predict without additional information

19. A ball rolling down an incline has its maximum kinetic energy at
a. bottom
b. halfway down
c. top
d. three-quarters of the way down

20. A TV set is pushed a distance of m with a force of 20n. how much work is done on the set?
a. 20j
b. 40j
c. 800j
d. 2j
e. 10j

21. A 2kg mass has 40j of potential energy with respect to the ground. Approximately how high is it above the ground?
a. 1m
b. 2m
c. 3m
d. 4m
e. none of these

22. A car moves 4 times as fast as another identical car. Compared to the slower car, the faster car has
a. 16 times the KE
b. 4 times the KE
c. 12 times the KE
d. 8 times the KE

23. A machine puts out 100 watts of power for every 1000 watts put into it. The efficiency of the machine is
a. 110%
b. 50%
c. 10%
d. 90%
e. none of these

24. A diver who weighs 500n steps off a diving board that is 10 m above the water. The diver hits the water with kinetic energy of
a. 10j
b. 500j
c. 5000j
d. more than 5000j
e. 510j

25. A 2500-N pile-driver ram falls 10m and drives a post 0.1 m into ground. The average impact force on the ram is
a. 250000 n
b. 2,500,000 n
c. 25,000n
d. 2500n